Sweet sorghum is one of potential energy crop in the tropical areas. EN6 is one of the super high biomass yield sweet sorghum imported from Japan. the authors contivated EN6 on different planting time (25/3, 15/4, 15/5, 15/6, 15/7 and 15/8) of the year 2012 and 2013 in Thai Nguyen province to evaluate effect of planting time on growth, yield and sugar content of this variety. The results show that, EN6 is strictly short day plant (only flower in the short day length). This variety therefore flower all in the middle of October regardless of plant time. The planting date had significantly affected on growth duration (from planting to harvest) of EN6. EN6 had longest growth duration when planted in Mar 25 (222 days). The length of growth duration reduced when EN6 was planted later and became shortest when EN6 was planted in August 15. Eventhough, the biomass and stalk yield of EN6 was highest when planted in March (131.2 tons/ha and 102.5 tons/ha, respectively) then April (129.8 and 98.1 tons/ha, respectively), the average amount of sugar accumulated per day was highest when EN6 was grown in June and then in May and July. The results suggested that EN6 can grow well in Thainguyen and the best time for planting EN6 is in June, May and then July. This research also shows that EN6 had some major pests that were stem borer, stalk rot and root rot There is a need to find good pest control method before growing EN6 in large scale.